xref: /openbmc/linux/arch/riscv/kernel/vdso/hwprobe.c (revision a9ebfc40)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Copyright 2023 Rivos, Inc
4  */
5 
6 #include <linux/types.h>
7 #include <vdso/datapage.h>
8 #include <vdso/helpers.h>
9 
10 extern int riscv_hwprobe(struct riscv_hwprobe *pairs, size_t pair_count,
11 			 size_t cpu_count, unsigned long *cpus,
12 			 unsigned int flags);
13 
14 /* Add a prototype to avoid -Wmissing-prototypes warning. */
15 int __vdso_riscv_hwprobe(struct riscv_hwprobe *pairs, size_t pair_count,
16 			 size_t cpu_count, unsigned long *cpus,
17 			 unsigned int flags);
18 
19 int __vdso_riscv_hwprobe(struct riscv_hwprobe *pairs, size_t pair_count,
20 			 size_t cpu_count, unsigned long *cpus,
21 			 unsigned int flags)
22 {
23 	const struct vdso_data *vd = __arch_get_vdso_data();
24 	const struct arch_vdso_data *avd = &vd->arch_data;
25 	bool all_cpus = !cpu_count && !cpus;
26 	struct riscv_hwprobe *p = pairs;
27 	struct riscv_hwprobe *end = pairs + pair_count;
28 
29 	/*
30 	 * Defer to the syscall for exotic requests. The vdso has answers
31 	 * stashed away only for the "all cpus" case. If all CPUs are
32 	 * homogeneous, then this function can handle requests for arbitrary
33 	 * masks.
34 	 */
35 	if ((flags != 0) || (!all_cpus && !avd->homogeneous_cpus))
36 		return riscv_hwprobe(pairs, pair_count, cpu_count, cpus, flags);
37 
38 	/* This is something we can handle, fill out the pairs. */
39 	while (p < end) {
40 		if (riscv_hwprobe_key_is_valid(p->key)) {
41 			p->value = avd->all_cpu_hwprobe_values[p->key];
42 
43 		} else {
44 			p->key = -1;
45 			p->value = 0;
46 		}
47 
48 		p++;
49 	}
50 
51 	return 0;
52 }
53